Sensory Differences between Commercialized Raw (unheated)- and Heated-Soy Sauces: Organization of Sensory Attributes to Evaluate Japanese Soy Sauce

Abstract

Recently, raw soy sauce without heat sterilization was developed and has become popular among consumers. Its sensory properties, however, have not been well studied. In this study, we aimed to reveal sensory differences between raw- and heated-soy sauces by conducting detailed sensory analysis. Quantitative descriptive analysis (QDA) was performed for 12 (6 raw/6 heated) commercially available soy sauces from six manufactures by 13 trained panelists. As a result, a total of 48 sensory attributes were identified. Statistical analysis revealed that raw soy sauce had stronger sweetness, umami and soy flavor, whereas heated soy sauce had stronger bitterness, astringency, metallic taste and bitter aftertaste. The differences in sweetness and bitterness of samples were supported by the results of chemical analyses. Further, we incorporated the 48 attributes into the 74 previously reported Japanese soy sauce attributes, for a total of 91 attributes. These 91 attributes were organized into a flavor wheel applicable to today’s Japanese soy sauce market. We also confirmed that the flavor wheel contained essential attributes commonly found in commercially available Japanese soy sauces and could effectively characterize these soy sauces. This is the first study to present sensory characteristics that can describe commercially available raw soy sauces. Furthermore, the schematization of soy sauce attributes will facilitate communication among stakeholders and contribute to the standardization, simplification and rapidity of Japanese soy sauce evaluation steps.